PC Based Up/Down Counter

PC Based Up/Down Counter counts up/down with position given by program. Up/Down counters can be constructed using discrete digital IC’s including up/down counters and 555 timers. This PC based up/down counter is also a simple design which facilities us to control the counting in up as well as down direction using PC. The program is written using ‘C’ language, which is very simple and easy to understand. The program incorporates various facilities like setting the counting starts and reset. Two 7-segment display drivers IC’s are used to display the count on 7-segment displays. You can count maximum ‘99’ counts. After ‘99’ counting starts from ‘00’ by simple modification in the program. You can easily set the time delay between the counts.

About the circuit :The circuit is very simple. It uses total five IC’s. IC1 is NOR gate IC which is used to give logic up/down. Pins 2,3,4,5 of 25-pin male D type connector are used as shown in figure. Pin 2 acts as an out port 1 which is used to give logic up pulse. Pin3 act as an out port 2 which is used to give clock pulses pin 5 acts as an outport port8 used to reset the count. When program runs, it asks for up/down counting. If the user enters up counting logic high pulse is applied to pin1 of IC1. Up/Down pin10 of IC2 and IC3goes high and starts up counting. Clock generated by the program is supplied to pin 15 of IC2 and IC3. The program also asks for number of up count. At that number the clock stops and display shows the count. If the user enters down counting, the program starts down counting from the count at which the clock set. You can also reset the count by giving logic high pulse to reset pin pin10 of IC2 and IC3. This is down through program. In the program, there are three options. It asks for up counting or down counting or reset. For up counting, you should press character ‘U’ OR ‘u. for down counting, you should press character‘d’ or ‘D’. For reset you should press ‘r’ or ‘R’.